Condenser



March 21, 1950 R. HORTON ETAL I pommussa 2 Sheets-Sheet 2;

Filed Oct. 22,1945

- .QLTTOPNEYS being progressive.

Patented Mar. 21, 1950 CONDENSER Ralph Horton, Groton,conn., and Martin H. I Olstad, Port Washington, N. Y., assiznora to Niagara .Blower Company, corporation of New York New ork, N. Y., a

. 7 Application October 22, 1945, Serial No. 623,814

Claims. (01. 257-2) This invention relates to a condenser and more particularly to a condenser for condensing the refrigerant, such as ammonia or Freon, in acompressor-condenser-expander system where lubricating oil is picked up by the refrigerant in the compressor. However, the use of the invento a much lower temperature than is possible with a dry coil.

Another object is to provide such an oil eliminator in combination with a condenser which tion is not limited to a refrigerating system and is applicable wherever the gas to be condensed contains a higher ,boiling point vapor which is advantageously removed from the gas as a part of the condensing process.

In a compressor-condenser-expander refrigera-' tion system, the gaseous ammonia, Freon or other refrigeration medium on being compressed in the compressor carries with it a part of the oil used to lubricate the compressor. The oil laden refrigerating medium is then condensed in the condenser and on being expanded in the expansion coil a part of the oil congeals in the expansion co l. The coating of oil thus built up on the inner surfaces of the expansion coil not only reduces the heat transfer eficiency of the coil but in time this coating cakes on the expansion coil surfaces so as to permanently impair the heat transfer, this reduction in heat transfer eificiency Further, with Freon, a constant addition of lubricating oil to the compressor -is required, and the present invention provides a controlled return of such oil to the compressor,

thereby to meet the lubricating requirements of 30 is, without special control, self-balancing under varying load and wet bulb conditions, such selfe balancing operating to remove the maximum amount of oil from .the fluid being condensed 'under all operating conditio W Another aim is to provide such an oil eliminator, in combination with a condenser, in which the maximum removal of oil from the" fluid being condensed under all load and atmospheric con-- ditions can be'placed under accurate instrument control.

Another object is to provide such an oil eliminator in combination with an evaporative type of condenser which will not scale, a feature of the invention residing in the removal of superheat from the gas to be condensed in an air coil and in which the temperature of the fluid is reduced to a point where scale does not form on the sprayed coil through which the fluid is subsequently passed to remove the latent heat of the fluid.

J Other objects and advantages will appear from the compressor as well as to efiect a'saving in oil.

It is one of the principal objects of this invention to provide, in combination with a condenser, means for removing the maximum amount of the following description and drawings in which: Fig. 1- is a front elevation of an evaporative type of condenser and Oil eliminator embodying the present invention.

Fig. 2 is an end elevational view thereof. Fig. 3 is an enlarged-vertical transverse -sectio taken on line 33, Fig. 1.

Fig. 4 is an enlarged vertical section through the shell of the oil separator.

oil from the fluid being'condensed thereby to T prevent such'oil from building up and caking on heat transfer surfaces over which the condensed fluid is subsequently passed- A further object is to provide such an oil eliminator in a condenser in which the oil is conveniently available for reuse.

Another object is to provide such an oil elimi nator which does not have any moving parts other than the necessary valves-to remove the oil collected therein. Y Another aim is to provide such an oil eliminator which is particularly adapted to an 'evaporative type of condenser in which the cooling eiTect is obtained principally from the evaporation of water on the cooling coil which is arranged in an air stream passing over the coil. Such an evaporative condenser has many times the cooling capacity of a dry coil of the same size and under normal conditions cools the fluid being condensed The invention is shown as embodied in a condenser having a sheet metal casing ill of rectangular form, the bottom of which is closed to form a tank or sump ll which contains a body of water i2 which is evaporated to provide the cooling effect. The tank H is shown as extended beyondone end of the casing, as indicated at i 3.

. A plurality of fan housings I5 are mounted in the upper part of the casing ID, the inlets of these fan housings being in communication with the interior of the casing Ill so as to exhaust air therefrom. A common shaft I6 extends through the several fan housings i5 anciis shown as driven by a rotor l8 mounted on a bracket I9 at one end of the casing l0. Within each fan housing the shaft l6 carries a fan 20 of any suitable construction, these-fans drawing the air from the interior of the casing l0 and discharging it through outlets 2| which project upwardly through the top of the casing I0. is admitted to the lower V The inlet 22 is shown as having fixed louvers 24 to prevent the escape of spr y water.- Both of the air inlets 22 and 23 extend substantially the full length of the casing l9.

Mounted on the side of the casing |ll over the air inlet opening 23 is a second sheet metal casing 25, this casing 25 extending substantially the full length of the casing II and including atop wall 26,-a side wall 28 and-opposite end walls 29 connedting these top and side walls 25, 28 with the adjacent side 'wallof the casing l beyond the ends of the air inlet opening 23 therein. Within this casing is arranged a series of hairpin tubes of a dry superheat coolingcoil 30, each having one leg connecting withan inlet header 3| and its other leg connecting with an outlet header 32. These headers are shown as arranged vertically, side by side, adjacent one end wall 29 of the casing, the inlet header 3| having at its upper end an inlet 33 for the hot gas to be condensed,

.and the outlet header 32 having an outlet 34 for the gases leaving the coil 30, these inlet and outlet connections 33, 34 extending through the adjacent end wall 29 of the casing 25. The air inlet opening 23 of the casing I0 is arranged at the bottom of the casing and from" the bottom of the air inlet opening 23 a bottom wall 35 extends half way across the lower otherwise open end of the casing 25. This bottom 35 of the casing 25 extends between the end walls 29 thereof and from the outer edge of this bottom wall 35 a central partition 36 extends upwardly through the casing 25 short of the top wall 26 thereof. This partition extends between the legs of the hairpin tubes and it will therefore be seen that the partition provides a U-shaped passage 38 for the air, the air entering through the inlet 39 and passing upwardly along the outer side of the partition 36 and thence downwardly along the inner side thereof and then passing out through the inlet opening 23 of the casing Hi. In its travel through the passage 38 this air passes in heat exchange relation with the tubes of the coil 3|] 4 I having heads at'its upperand lower ends. The

. 4 1 I shown as oomprisinga vertical cylindrical shell outlet 34 from the superheat or prlmarycoollng coil 3|] is connected with an inlet pipe 42 extendwardly moving column of gas within the separator shell 4|. This gas escapes through an outlet pipe 44 extending through the side wall of the shell 4| near the topthereof. The inlet end of this pipe 44 is bent upwardly and arranged coaxially of the shell 4|. Further, to impede the cuit from theinlet 42 to'the outlet 44. In passin the casing 25, this coil being a dry primary 7 coil to remove the superheat from the gases being condensed.

This dry primary superheat cooling coil 30 is proportioned to remove only the superheat from the gases to be condensed and to a temperature slightly above the condensing temperature of these gases. It has been found that the gas at this temperature presents the optimum conditions for the separation of the maximum amount of oil therefrom by a simple oil separator. At higher temperatures the oil tends to remain in a volatile state and since both the gas to be condensed and the oil are ina vapor state, the separation through their difierence in specific gravity is difficult. At lower temperatures condensation of the gas to be condensed takes place and hence since both the oil and the condensate are in a liquid state the separation through their difference in specific gravity is diflficult. At the critical temperature of the fluid to be condensed just above its condensing temperature the fluid to be condensed is in a gaseous state and the oil This separator, indicated generally at 40, is

ing through the separator shell 4| the velocity of the gas is greatly reduced, particularly as the downwardly moving helically rotating column of gas is slowed almost to a standstill before it can escape in a reverse direction to the top of the separator casing. Further, the direction. of movement oiithe gas is constantly and abruptly being changed. With such reduction in velocity and change in direction of the flow of gas, the condensed oil separates from the gas and drops to the bottom of the separator shell 4|.

The level of oil in the bottom of the separator shell 4| can be observed through a sight glass 48. When a sufficient amount of oil accumulates in the separator shell 4|, as indicated by the sight glass 48, an oil drain valve 49 in the bottom of the shell 4| can be opened to withdraw the ac-' cumulated oil. In an ammonia system this withdraw'al can be through a rubber hose into a bucket. In a Freon system the drain valve 49 would be connectedto the crank case oi-the compressor. To drain such ammonia as condenses in the separator 4|], an ammonia drain pipe 50' is provided in the bottom of the oil separator shell 4|, this ammonia drain pipe 50 extending a substantial distance upwardly into the shell and'being provided with an ammonia drain valve 5|. The ammonia has a lower specific gravity than the oil and hence after the oil has been drained below the level of the top of the ammonia drain pipe 50, as indicated by the sight glass 45, it will be seen that any liquid ammonia in the separator can be drained by opening the ammonia drain valve 49.

From th outlet pipe 44 of the oil separator 40, the gas passes into the inlet 55 of an inlet header 56 of a secondary or condensing coil 58 arranged across the interior of the casin in immediately above the air inlet 22 thereof. The tubes 59 of this coil 58 can be of hairpin form, each having one leg connected with the inlet header 56 and its opposite leg connected with an outlet header B8. The outlet for the condensate from the coil 58 can connect with a line 5| lead- 5 withdraws water from the body I2 01' water in the sump or tank II at the bottom of the casing l0. Makeup water can be supplied to this body I2 of water in the sump ll in-any usual and well known manner.

The usual eliminator plates 81 are arranged above the sprays 63 to remove entrained water from the air stream.

In the operation of the condenser and oil separator, as above described, two streams of atmospheric air are drawn into the casing II) by the fan wheels 20 and discharged through the fan casing outlets 2| extending through the top of the casing 10. One of these air streams enters the casing 25 through its-inlet 39 and travels up and then down the U-shaped passage-38 provided in this casing by the partition 36 and thence is drawn into the casing l through its air inlet opening 23. The other air stream enters the air inlet opening 22 at the bottom of the casing l0 and travels upwardly through the interior of this casing.

The first air stream passes the tubes of the dry primary or superheat cooling coil and thereby cools the gas to be condensed in this primary coil and which enters at 33 and leaves at 34. This primary or superheat cooling coil 30 is p p tioned to remove the superheat from the gas to be condensed and to cool it to a temperature slightly above its condensing temperature. The gas to be condensed thercforeleaves this primary dry superheat coil in the formof a gas and at a temperatur slightly above its condensing temperature.

At this temperature it has been found that the maximum amount of oil can be separated from the fluid to be condensed. In cooling the gas to be condensed to this temperature slightly above its condensing temperature th oil vapor in the gas is condensed so that it is in liquid form. At the same time the fluid to be condensed is still in the form of a gas so that the separation is of a liquid from a gas and not of aliquid from a liquid as would be the case if the temperature of the gas to be condensed were permitted to fall below its condensing temperature.

To separate the entrained liquid oil from the gas to be condensed it passes from the outlet 34.

of theprimary dry superheat cooling coil 30 to the tangential and downwardly directed inlet pipe 42 extending through the cylindrical wall of the shell 4| of the oil separator 40; The inlet velocity sets up a downwardly moving and rotating column of gas in this separator shell, the gas from which escapes upwardly in opposition to this downwardly moving column; In so escaping these gases pass around the bafiie 46 and thence through the upwardly directed central inlet of the outlet pipe 44. In so traveling through the shell '4] of the oil separator 40 the velocity of the gas is greatly reduced and the direction of its flow changed whereby the entrained oil falls by gravity to the bottom of the separator casin 4|. oil can be removed through the oil drain 49 and any superposed liquid body of the fluid to be condensed can be removed through .the drain line 50,

the conditions within the separator shell being observable through the sight glass 48.-

From the outlet 44 of the oil separator the gas passes to the inlet 55 of the condensing coil 58, this coil being arranged in the casing I0 and across the stream of air flowing upwardly therethrough from the air inlet 22. This coil is sprayed with water withdrawn from the body I2 The accumulation of this ,01' water in the sump or tank II at the bottom of the casing lit by the pump 68 and. discharged. from the spray pipe 85' and its branches 6! a through the nozzles 83 against the tubes 59:91

thiscoil 58.

The cooling oi the fluid passing through the wetted. condensing coil id is thereby eflected essentially by the evaporation of the water sprayed on these coils. At the same time the fluid being treated has been cooled to such an extent on passing through the dry primary superheat cooling coil 30 that there is no tendency for scaleto form on the condensing coil 58 from the water sprayed thereon. By employing evaporative many times the cooling capacity of a dry surface evaporative cooling coil operates inresponse to the wet bulb temperature of the 'outsideair and since under normal conditions th wet bulb temperature of the outside air is substantially lower than its drmbulb temperature, the condensate leaves at a very much lower temperature. This condensate leaves the outlet header 6|! of the secondary evaporative cooling coil 58 through the is self-balancing in response to variations in load and in response to variations in atmospheric conditions influencing the operation of the condenser. Under normal conditions the outside dry bulb temperature rises and falls with the outside wet bulb temperature. With a light load upon the condenser, or a low wet bulb temperature of the outside air drawn into the air inlet 22 greater cooling is effected by the sprayed condenser coil 58 and consequently the head 4n pressure drops-. The condensing temperature rises and fallswith the head pressure and hence under light load or low wet bulb conditions the condensing temperature of the gas being con-- At the same time with such a light load or low dry bulb temperature of the densed drops.

outside air the primary-dry superheat cooling coil 30 cools the gas to be condensed to a lower temperature. Hence, with light load or low outside wet and dry bulb conditions, while the head is lowered, the primary dry superheat coil 30 effects a greater amount of cooling and hence brings the gas to itslowered condensing tem perature.

er head pressure and higher condensing temperature is maintained b the sprayed condensing coil 58 and at thesame time, because of the higher entering temperature of the gas or the 0 higher dry bulb temperatureof the outside air the primary cooling coil 30 is less efiective and the gas leaves this coil at a higher temperature. The apparatus is self-balancing, therefore, in that under varying load or outside temperature conditions the sprayed coil 58 adjusts .th head pressure and connecting temperature to accord with the increased or decreased cooling effect of the dry primarycoil 30. Hence this dry pri mary superheat cooling coil 30 can be designed to bring the gas closeto but not below the condensing temperature under all normal conditions of operation. Q

While the apparatus as above described is selfbalancing, for greater accuracy of control, par- 15 cooling with this secondary coil 58, this coil has cooling coil" of the same size. Further, since an 50, pressure and condensing temperature of the gas Conversely, with heavy load or high 5 outside wet bulb temperature conditions, a highticularly in bringing the gas leaving the dry privariations in climatic conditions.

mary superheat coil 30 accurately to a temperature slightly above its condensing temperature under all conditions oi operation, it may be desirable to provide a positive thermostatic control. For this purpose a damper 68 is shown as arranged in the air inlet opening 23, this damper being actuated by a damper motor 69. This damper motor is controlled by a sub-thermostat lfl the sensitive parts of which are immersed in the gas entering the dry primary superheat cooling oil 30 through the line 33. The setting of this sub-thermostat 70 is in turn controlled by a master thermostat II which is responsive to temperature changes of the condensate leaving through the outlet line 6|. By this arrangement the amount of cooling eiiected by th dry primary pro-cooling coil 30 is adjusted in accordance with the entering temperature of the gas to be condensed. Thus, if the temperature of the gas entering at 33 should rise, the sub-thermostat 10 in this line actuates the damper motor 69 to open the damper 68 and hence admit more air to the dry primary superheat cooling coil 30. In consequence more cooling is eifected by this primary coil 30 and henc the gas leaves this primary coil 30 slightly above vapor, a liquid separator adapted to separate a liquid from a gas, means for passing the gas leavcondensing coil, and means for discharging and distributing water over said secondary condensing coil to wash the exterior of said secondary condensing coil and to evaporate and absorb heat therefrom thereby to reduce the temperature of the gas passing therethrough close to the wet bulb temperature of said atmospheric air and to condense said gas passing therethrough.-

2. In a condenser for gases containing a higher boiling point vapor, a casing having two air inits condensing temperature even though its entering temperature is higher. If, however, this condensing temperature should, say, lower, due to a falling head pressure in the outlet line of the condenser, th master thermostat H, responsive to the leaving temperature of the condensate, and hence its head pressure, adjusts the setting of the sub-thermostat l0. ting would be adjusted downwardly whereby the sub-thermostat 10, through the damper motor 69, would further open the damper 68. This would lower the temperature of the gas leaving the dry primary superheat cooling coil thereby bringing this leaving temperature close to the lowered condensing temperature responded to by the master thermostat II. It will therefore be seen that the master and sub-thermostats in combination insure that the tempera ture of the gas leaving the dry primary superheat cooling coil 30 is at all times close to but higher than the condensing temperature of the gas regardless of varying head pressures or climatic conditions.

From the foregoing it will be seen that with the condenser and oil separator forming the subject of this invention the oil is extracted from the gas to be condensed when the temperature of this gas is slightly above the condensing temperature of the gas and when conditions are most favorable to oil separation. Further, with or without the thermostat controls the condenser is self-balancing to insure the oil separation from the gas when ciose'to but above its condensing temperature regardless of variations in load' or With this balanced operation and with the resulting removal of the maximum amount of oil the tendenc of the oil to congeal and cake on the tubes of the evaporating coil to thereby reduce and destroy its heat transfer efiiciency is largely eliminated.

We claim as our invention: 7 1. In a condenser for gases containing a higher This setlets, a fan drawing separate streams of atmospheric air into said casing through said two air inlets, a primary cooling coil in the path of the stream of air entering one of said air inlets and cooled thereby, said primary coil being proportioned to remove the superheat from said gas and to reduce its temperature close to the dry bulb temperature of the atmospheric air thereby to condense said higher boiling point vapor, a liquid separator adapted to separate a liquid from a gas, means for passing the gas leaving said primary coil through said liquid separator to remove said condensed higher boiling point vapor, a secondary condensing coil in the path of the stream of air entering the other of said air inlets and cooled thereby, means for passing the gas leaving said liquid separator through said secondary condensing coil, and means for discharging and distributing water over said secondary condensing coil to wash the exterior of said secondary condensing coil and to evaporate and absorb heat therefrom thereby to reduce the temperature of the gas passing therethrough close to the wet bulb temperature of said atmospheric air and to condense said gas passing therethrough.

3. In a condenser for gases containing a higher boiling point vapor, a casing having an air inlet at its upper end and a second air inlet near its lower end, a fan in the upper part of said casing and drawing separate streams of atmospheric air into said'casing'through said two air inlets, a dry primary cooling coil in the path of the stream of air entering said first air inlet and cooled thereby, said dry primary coil being proportioned to remove the superheat from said gas and to reduce its temperature close to the dry bulb temperature of the atmospheric air thereby to condense said higher boiling point vapor, a liquid separator adapted to separate a liquid from a gas, means for passing the gas leaving said dry primary coil through said liquid separator to remove said condensed higher boiling point I vapor, a secondary condensing coil in said casing boiling point vapor, a primary dry cooling coil,

means for passing air over said dry primary coil to absorb heat therefrom, said dry primary coil being proportioned to remove the superheat from in the path of the stream of air entering said second air inlet and cooled thereby, means for passing the gas leaving said liquid separator through said secondary condensing coil, and means for discharging and distributing water over said secondary condensing coil to wash the exterior of said secondary condensing coil and to evaporate and absorb heat therefrom thereby to reduce the temperature of the gas passing therethrough close to the wet bulb temperature of said atmospheric air and to condense said gas passing therethrough.

4. In a condenser for gases containing a higher boiling point vapor, a casing having an air inlet at its upper end and a second air inlet near its lower end, a second casing secured to the exterior of said first casing and through which the air entering said first air inlet is required to pass, a

v I fan/,in the upper part of said first casing and drawingseparate streams of atmospheric air into said first casing through said two air inlets, a

- dry primary cooling coil in said second casing in the path of the air entering said first air inlet and cooled thereby, said dry primary coil being proportioned to remove the superheat from said 'gas and to reduce its temperature-close to the dry temperature of the condensate leaving said secondary condensing cofl, and means actuated by said sub-thermostat and controlling the now of bulb temperature of the atmospheric air therebyremove said condensed higher boiling point vapor, a secondary condens ng coil in said'first casing in the path of the stream of air entering said second air inlet and cooled thereby, means for passing the gas leaving said liquid separator through said secondary condensing coil, and means for discharging and distributing water over said secondary condensing coil towash the exterior of said secondary condensing coil, and to evaporate and absorb heat therefrom thereby to reduce the temperature of the gas passing therethrough close to the 'wet bulbltemperature of said atmospheric air and to condense said gas passing therethrough.

' 5. In a condenser for gases containing a higher boiling point vapor, a primary cooling coil, means for passing air over said primary coil to absorb heat therefrom, said primary coil beingproportioned to remove the superheat from said gas and to reduce its temperature close to the dry bulb temperature of the air passing thereover thereby to, condense said higher boiling point vapor, a liquid separator adapted to separate a liquid from a gas, means for passing the gas leaving said primary coil through said liquid separator to remove said condensedhigher boiling point vapor, a secondary condensing coil, nieans for passing the gas leaving said liquid separator through said secondary condensing coil, said secondary condensing coil being maintained at a temperature to condense said gas. passing, therethrough, a thermostat responsive to the temperature of said gas being condensed, and means actuated by said thermostat and controlling the flow of said air' over said primary coil to maintain the temperasaid air over said dry primary coil to maintain the temperature of the gas leaving said dry primary coil close to and above the condensing temperature-thereof atall head pressures at the outlet fronr said secondary condensing coil.

7. In a condenser for gases containing a higher I boiling pointvapor, a casing having two air inlets, a fan drawing separate streams of at'mospheric air into said casing through said two air inlets, a primary cooling coil in the path of the stream ofv air entering one of said air inlets and cooled thereby, said primary coil being proportioned to remove the superheat from said gas and to reduce its temperature close to the dry bulb "temperature of the atmospheric air thereby to condense said high'er boiling point vapor, a liquid separator adapted to'separat'e a liquid from a gas, means for passing the gas leaving said primary coil through said liquid separator to remove said condensed higher boiling point ,vapor, a secondary condensing coil in the path of the stream of air entering the other of said air inlets and cooled thereby, means for passing the gas leaving said liquid separator through said secondary condensing coil, means for throttling the air en- 7 te'ring said one of said air inlets supplyingair to said primary cooling coil, and a thermostat responsive to the temperature of said gas being condensed and controlling said throttlingsmeans to maintain the temperature of the gas leaving said primary coil close to and above the condensing temperature thereof.

8. In a condenser for gases containing a higher boiling point vapor, a casing havingtwo air inlets, a fan drawing separate streams of atmospheric air into said casing through said two air inlets, a dry primary cooling coil in the path of.

thestream of air entering one of said air inlets and cooled thereby, said dry primary coil being proportioned to remove the superheat from said gas and to reduce its temperature close to the dry bulb temperature of the atmospheric air thereby to condense said higher boiling point vapor, a liquid separator adapted to separate a liquid from a gas, means for passing the gas leaving said dry primary coil through said liquid separator to remove said condensed higher boiling point vapor, a secondary condensing coil in the ture of the gas leaving saidprimary coil close to and above the condensing temperature thereof.

6. In aco'ndenser for gases containing a higher boiling point vapor, a primary dry cooling coil, 'means for passing air over said dry primary coilto absorb heat therefrom, said dry primary coil being proportioned to remove the superheat from said gas and to reduce its temperature close to the dry bulb temperature of the air passing thereover thereby to condense said higher boiling point vapor, a liquid separator adapted to s ep arate a liquid froma gas, means for passing the of said sub-thermostat and responsive to their path of the stream ofair entering the other of said air' inlets and cooled thereby, means for passing the gas leaving said liquid separator through said secondary condensing coil, means for throttling the air entering said one of said air inlets supplying air to said primary cooling coil, a sub-thermostat responsive to the temperature of the gas entering said dry primary coil, a master thermostat controlling the setting of said sub-thermostat and responsive to the temperature of the condensate leaving said secondary condensing coil, and means operatively connecting said sub-thermostat with said sthrottling means to maintain the temperature of the gas leaving said dry primary coil close to and above the condensing temperature thereof at all head I 'pressures at the outlet from said secondary condensing coil. I

9. In a condenser for gases containing a higher boiling point vapor, a primary cooling coil, means for passing air over said primary coil to absorb heat therefrom, said primary coil being proportioned to remove the superheat'from said gas and o reduce its temperature close to the dry bulb temperature of the air passing thereover thereby to condense said higher boiling point vapor, a liquid separator, a liquid separator adapted to separate a liquid from a. gas, means for passing the gas leaving said primary coil through said liquid separator to remove said condensed higher boiling point vapor, a secondary condensing coil, means for passing the gas leaving said liquid separator through said secondary condensing coil, means for passing atmospheric air over said secondary condensing coil, means for discharging and distributing water over said secondary condensing coil to wash the exterior of said secondary condensing coil and to evaporate and absorb heat therefrom thereby to reduce the temperature of the gas passing therethrough close to the wet bulb temperature of said atmospheric air and to condense said gas passing therethrough, a thermostat responsive to the temperature of said gas being condensed, and means actuated by said thermostat and controlling the flow of air over said primary coil to maintain the temperature of the gas leaving said primary coil close to and above the condensing temperature thereof.

10. In a' condenser for gases containing a higher boiling point vapor, a primary dry cooling coil, means for passing air over said dry primary coil to absorb heat therefrom, said dry primary coil being proportioned to remove the superheat from said gas and to reduce its temperature close to the dry bulb temperature of the air passing thereover thereby to condense said higher boiling point vapor, a liquid separator adapted to separate a liquid from a'gas, means for passing the gas leaving said dry primary coil through said liquid separator to remove said condensed higher boiling point vapor, a secondary condensing coil, means for passing the gas leaving said liquid separator through said secondary condensing coil,

means for passing atmospheric air over said sec ondary condensing coil, means for discharging and distributing waterover said secondary condensing coil to wash the exterior of said secondary condensing coil and to evaporate and absorb heat therefrom thereby to reduce the temperature of the gas passing therethrough close to the wet bulb temperature of said atmospheric airand to condense said gas passing there- 'through, a sub-thermostat responsive to the temperature of the gas entering the dry primary coil, a master thermostat controlling the setting of said sub-thermostat and responsive to the temperature of the condensate leaving said secondary condensing coil, and means actuated by said subthermostat and controlling the flow of said air over said dry primary coil to maintain the temperature of the gas leaving said dry primary coil close to and above the condensing temperature thereof at all head pressures at the outlet from said secondary condensing coil.

RALPH HORTON. MARTIN H. OLSTAD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

